Wireless temperature sensing and control system for metal kiln and method of using the same

ABSTRACT

A rotary aluminum kiln temperature regulation system comprising a temperature sensing device in the kiln that is configured to take temperature readings in an area of the kiln in proximity to the temperature sensing device. The system including a wireless transmitter operatively associated with the temperature sensing device and a receiver wirelessly associated with the transmitter, such that the transmitter and receiver wirelessly transmit the temperature readings taken by the temperature sensing device from the transmitter to the receiver. The system also including a control unit operatively connected to the receiver that is configured to receive the transmitted temperature readings and determine when the transmitted temperature readings exceed a predefined temperature setpoint. The control unit is operatively connected to a heat flow control device that can adjust heat flow inside the kiln in proximity to the temperature sensing device, such that the control unit regulates the heat flow control device to maintain a desired level of heat flow in the kiln in proximity to the temperature sensing device in response to the temperature readings transmitted from the temperature sensing device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application derives and claims priority from U.S. provisionalapplication 61/346,199 filed 19 May 2010, which application isincorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

This invention relates principally to a metal furnace or kiln, and moreparticularly to a temperature sensing and control system for rotaryaluminum delacquering kilns using wireless thermocouples or comparabletemperature sensing devices.

It has for some time been a standard practice to recycle scrap metals,and in particular scrap aluminum. Various furnace and kiln systems existthat are designed to recycle and recover aluminum from various sourcesof scrap, such as used beverage cans (“UBC”), siding, windows and doorframes, etc. One of the first steps in these processes is to use arotary kiln to remove the paints, oils, and other surface materials onthe scrap aluminum (i.e. “feed material”). This is commonly known in theindustry as “delacquering.” Delacquering is typically performed in anatmosphere with reduced oxygen levels and temperatures in excess of 900degrees Fahrenheit. The temperature at which the paints and oils andother surface materials are released from the aluminum scrap in the formof unburned volatile gases is known as the “volatilization point.” Onesuch typical aluminum recycling system utilizes a rotary kiln todelacquer the aluminum. Many of these systems utilize a recirculatingheat apparatus comprising a burner with a blower to direct heat into thekiln, and a recovery device that collects exhaust heat from the kiln andrecirculates the recovered heat into the heat flow for the kiln.

Due to the difficulties in accessing the rotating material duringoperation, the temperatures in traditional rotary aluminum kilns are notregularly monitored. Sensing devices external of the kiln are sometimesused as a temperature testing method. This requires manual interventionand is not particularly accurate. Unfortunately, failure to consistentlyand accurately monitor the conditions in the kiln can lead to fires.These fires result when the feed material reaches the volatilizationpoint too rapidly and the feed material begins to rapidly oxidize andgenerate its own heat, leading to a high temperature excursion (i.e.“overtemp event”). Applicants have learned through tests, utilizingwireless high temperature thermocouples placed in the kiln, that certaintemperature profiles occur in the feed material that can be used asprecursors to predict such high temperature excursions or overtempevents, and that such events can arise in as little as 10 minutes ofoperation and can arise in different locations within the kiln. Further,applicants have learned through testing that controlling the heat flowinto the kiln can regulate and prevent such overtemp events. Theseovertemp events can occur at different positions along the length of thefeed material in the kiln, and may be affected by such variables as thesize of the feed material put into the kiln, the moisture content of thefeed material, the volume of the feed material and the feed rate, thecomposition of the feed material, and the cleanliness of feed material.A fire in a rotary aluminum kiln can require a costly shut-down, willlikely destroy the feed material, and can damage the kiln and otherassociated equipment.

One example of a condition that can lead to an overtemp event concernsthe presence of magnesium in aluminum feed material. Most aluminum cans(e.g. UBC's) have lids or tops that comprise a higher percentage ofmagnesium than the body of the can. Magnesium melts at a lowertemperature than aluminum, and is very combustive. When placed in arotary aluminum kiln, the aluminum can lids can separate from thealuminum can body. This is known in the industry as “lid fracturing”.This lid fracturing reduces the lids to particles of aluminum andmagnesium as small as a grain of sand. Oxidation of these particles inthe kiln occurs very rapidly, resulting in highly combustible partiallyoxidized aluminum and magnesium. The amount of heat in the kiln must bereduced or the partially oxidized aluminum and magnesium can acceleratein temperature and ignite in the kiln. Like other overtemp events, suchUBC lids fracture events can be localized to one or more zones withinthe kiln. However, once ignition occurs the fire can flash rapidlythroughout the kiln.

As will become evident in this disclosure, the present inventionprovides benefits over the existing art.

BRIEF DESCRIPTION OF THE DRAWINGS

The illustrative embodiments of the present invention are shown in thefollowing drawings which form a part of the specification:

FIG. 1 is a schematic of an aluminum rotary kiln delacquring systemincorporating one embodiment of the present invention;

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION

In referring to the drawings, a schematic embodiment of the novelwireless temperature sensing and control system for metal kiln 10 of thepresent invention is shown generally in FIG. 1, where the presentinvention is depicted by way of example as integrated into arepresentative mass flow delacquering system X with a rotary aluminumkiln 12 having a delacquering zone 13 within the kiln 12. As can beseen, a set of four independent high temperature thermocouples 14, 16,18 and 20, are positioned along the length of the kiln 12. In practice,the thermocouples 14, 16, 18 and 20 are positioned with at least thetemperature sensing portion of the thermocouple exposed to thedelacquering zone 13 within the rotary kiln 12. All of the thermocouples14, 16, 18 and 20 are configured to detect temperature readings in thekiln 12, including temperature readings in excess of the melting pointof aluminum, and are further configured to transmit the temperaturereadings they sense inside of the kiln 12 via radio signals to areceiving device or receiver 22 that is external of the kiln 12.Alternately, the thermocouples 14, 16, 18 and 20 could be operativelyconnected to a wireless transmitter (not shown) that would transmit thetemperature readings to the receiving device or receiver 22.

Aluminum feed material 26, which is ready for the delaquering process,is supplied to the kiln 12 through a feed material control chute 11,which regulates the rate at which the feed material is supplied to thekiln 12. The material then travels through the kiln 12 as the kiln 12rotates about its central axis, and the material 26 is then dischargedthrough a discharge chute 15, which regulates the rate at which feedmaterial is discharged from the kiln 12. In order to reach and maintaintemperatures sufficient to delacquer aluminum feed material 26 in thedepicted system X, the kiln 12 receives heated air from a burner 30 anda burner bypass pipe 32. The burner 30 receives ambient temperature air,at a temperature of approximately 70 degrees F., from a combustionblower 34 and recirculated gases, at a temperature of approximately 500degrees F., from a variable speed recirculation blower 36 which in turnreceives the recirculated heated gases that have passed through the kiln12. Combustion gases are controllably supplied to the burner 30 througha mass flow controller 31. The combustion blower 34 also drives theambient temperature air into an afterburner 35 attached to the burner30. Oxygen can be controllably injected as desired directly into theafterburner 35 through a mass flow controller 37. A thermocouple 39positioned near the exit for the afterburner 35 takes temperaturereadings of the gases as they exit the afterburner. The thermocouple 39connects to the combustion gas mass flow controller 31 and a mass flowcontroller 41, positioned between the combustion blower 34 and theburner 30, such that the mass flow controllers 31 and 41 regulate theflow of combustion gases and air, respectively, in response to thetemperature readings from the thermocouple 39, so as to automaticallycontrol the burner operation to control the temperature of the gasessupplied through a supply pipe 114.

Because the recirculation blower 36 simultaneously supplies preheatedair to the burner 30 and the kiln 12, the volume of heated air suppliedto the kiln 12 in system X can be predictably controlled by varying thespeed of the blower 36. Because the volume of heated air supplied to thekiln 12 in turn affects the amount of heat injected into the kiln 12 andthereby to the feed material 26 in the delacquering zone 13 within thekiln 12, varying the speed of the blower 36 has a and controllablepredictable impact on the amount of heat applied to the feed material 26in the delacquering zone 13.

The receiver 22 is operatively connected to a programmable control unit24, although in other configurations the control unit 24 can comprisethe receiver 22. Of course, wires or wireless devices may alternativelybe used to operatively connect components positioned outside the kiln 12or outside the gas and material flow components of the system X. Hence,for example, the receiver 22 may be wired to or wirelessly connected tothe control unit 24. The kiln temperatures transmitted from thethermocouples 14, 16, 18 and 20 to the receiver 22 are communicated tothe control unit 24. In traditional configurations, an automatedfeedback loop adjusts the speed of the blower 36 in response to thequantity and rate of feed material directed into the kiln 12. In thepresent configuration of FIG. 1, the control unit 24 is operativelyconnected to and controls a mass flow controller 40 that regulates thespeed of the recirculation blower 36, and thereby the heat applied tothe feed material 26 in the delacquering zone 13 within the kiln 12. Thecontrol unit 24 may be wired to or wirelessly connected to the mass flowcontroller 40. The control unit 24 automatically controls the speed ofthe blower 36, using commands to the mass flow controller 40, based upona predetermined process loop control algorithm programmed into thecontrol unit 24.

As seen in FIG. 1, in a representative mass flow delacquering system X,gases exiting the kiln 12 travel through an exit pipe 100, where abypass pipe 102 joins the exit pipe 100. The temperature of the gasestraveling in this area of the system X is approximately 500 degrees F.The gases are then directed into a cyclone 104, through an inlet pipe106 into the recirculating blower 36. The blower 36 both draws the gasesfrom the cyclone 104 and pushes the gases into supply pipe 108. Adiverter valve 110 is positioned at a junction along the pipe 108 todirect the gas flow into an afterburner 35 or through the burner bypasspipe 32. Gases directed into the afterburner 35 are subjected to theheat generated by the burner 30, where the gas temperature is raised toapproximately 1500 degrees F. The gases are then directed out of theafterburner 35 and directed along the supply pipe 114 to the kiln 12.

Near the afterburner 35, the bypass pipe 102 is connected to the supplypipe 114, where a portion of the gases are diverted to the exit pipe100. The amount of gas that is allowed to exit through the bypass pipe102 is controlled by a bypass valve 116. The bypass valve 116 is, inturn, connected to a thermocouple 118 in the exit pipe 100, and thevalve 116 opens and closes in response to the temperature readingssupplied by the thermocouple 118.

Downstream from the junction of the bypass pipe 102 and the supply pipe114, a vent pipe 120 joins the supply pipe 114. The vent line connectsto a pressure control damper 122 and, through which the gas pressure inthe system X can be controlled. In addition, an emergency vent stack124, that is triggered by temperature readings supplied from athermocouple 126 in the supply pipe 114 near the exit for theafterburner, connects to the vent pipe to provide for a safety pressurerelief for the system X.

Before entering the kiln 12, the supply pipe 114 is joined by the burnerbypass pipe 32. By utilizing the diverter valve 110 to controllablycombining the higher temperature gases supplied by the afterburner withthe lower temperature gases supplied by the bypass 32, the user canregulate the temperature of the gases supplied to the kiln 12. A nominaltarget temperature for a typical delaquering operation is approximately1100 degrees F. The diverter valve 110 is connected to a thermocouple128 in the supply pipe 114 near the entrance to the kiln 12, and thevalve 110 rotates to control the ratio of gases directed into theafterburner 35 as opposed to the bypass 32, in response to thetemperature readings supplied by the thermocouple 128.

A thermocouple 130 near the junction of the kiln 12 and the exit pipe100 takes temperature readings of the gases as they exit the kiln 12.This temperature data provides an additional source of information toalternatively control the mass flow controller 40. The temperaturereadings from thermocouple 130 may be used separate from or inconjunction with the operation of the control unit 24.

A pressure sensor 132 is positioned in the supply pipe 114 near theentrance to the kiln 12. The pressure sensor 132 is connected to andcontrols the pressure control damper 122 in the vent stack 120.

Upon initial setup, the wireless thermocouples 14, 16, 18 and 20 can beused to profile the temperatures along the inner length of the kiln 12.This profile is then programmed into the control unit 24 as a baselinefrom which overtemp events are detected and to which a response isperformed. During operation of the system X, the control unit 24constantly and automatically monitors the kiln 12 via the temperaturesreceived from each of the wireless thermocouples 14, 16, 18 and 20. Thealgorithm in the control unit 24 is programmed to use the baselineprofile to monitor for spikes or unacceptable increases in temperaturein the feed material 26 in the delacquering zone 13 within the kiln 12,and automatically control the heat supplied to the kiln 12 to preventfires in the kiln 12 and otherwise maintain a proper operationaldelacquering profile within the kiln 12.

In a simple form, and by way of example, should any one or more of thethermocouples 14, 16, 18 and 20, detect a temperature that exceeds apredetermined high limit setpoint for a period of time that exceeds apredetermined duration, or should one or more of the thermocouples 14,16, 18 and 20, detect an abnormal temperature pattern in the kiln 12such as a rapid rise in temperature, the control unit 24 thenautomatically instructs the mass flow controller 40 to decrease thespeed of the blower 36 a predetermined amount based upon the anticipatedreduction in heat that is necessary to avoid a fire in the kiln 12, asformulated from tests and calculations. Should the temperatures in thekiln 12 drop below a lower limit setpoint for a period of time thatexceeds a duration setpoint, the control unit 24 then automaticallyinstructs the mass flow controller 40 to increase the speed of theblower 36 a predetermined amount based upon the anticipated increase inheat that is necessary to properly operate the kiln 12, also asformulated from tests and calculations. Of course, one skilled in theart will recognize that much more complex algorithms may be incorporatedin the control unit 24 to enable refined control of the temperatureprofile of the feed material 13 and the and the efficiency of the kiln12.

In an even more simplified variant of the novel wireless temperaturesensing and control system for metal kiln 10 of the present invention(not shown), there is no control loop to automatically control the heatsupplied to the kiln 12. Rather, when an overtemp event is identified bythe control unit 24 from the wireless thermocouples 14, 16, 18 and 20,such as for example when any one or more of the thermocouples 14, 16, 18and 20, detects a temperature that exceeds a predetermined high limittemperature setpoint for a period of time that exceeds a predeterminedduration, or should one or more of the thermocouples 14, 16, 18 and 20,otherwise detect an abnormal temperature pattern in the kiln 12 such asa rapid rise in temperature, the control unit 24 generates anotification. The notification can activate a notification apparatus,such as triggering an alarm (not shown) to alert the system X operatorsof a potential fire threat in the kiln 12. The system X operators canthen inspect the situation and make any manual or automated adjustmentsto the system X operation as they see fit.

Of course, the programmable control unit 24 may be operatively connectedto and control in response to the temperature readings from any one ormore of the thermocouples 14, 16, 18 and 20, any one or more of the heatflow control devices in the system X, which include for example andwithout limitation, the pressure control damper 122, the combustionblower 34, the combustion oxygen supply mass flow controller 37, thecombustion gas mass flow controller 31, the combustion air mass flowcontroller 41, the diverter valve 110, the emergency vent 124, thebypass valve 116, the feed material control chute 13 and the feedmaterial discharge chute 15.

While we have described in the detailed description two configurationsthat may be encompassed within the disclosed embodiments of thisinvention, numerous other alternative configurations, that would now beapparent to one of ordinary skill in the art, may be designed andconstructed within the bounds of our invention as set forth in theclaims. Moreover, both of the above-described novel wireless temperaturesensing and control system for metal kiln 10 of the present inventioncan be arranged in a number of other and related varieties ofconfigurations without expanding beyond the scope of our invention asset forth in the claims.

For example, the system 10 is not necessarily required to be installedin a mass flow delacquering system X as depicted in FIG. 1, but may beinstalled or otherwise incorporated into a variety of configurations ofmetal recycling furnace and kiln systems. Further, the system 10 is notconstrained to the use of four wireless thermocouples such as 14, 16, 18and 20. Rather, the system 10 may comprise any number of wirelessthermocouples (or other temperature sensing devices), from as few as asingle wireless thermocouple up to numerous more than four wirelessthermocouples. Likewise, the system 10 is not restricted to a singlereceiver 22 or a single control unit 24. Depending on the configurationof the recycle system and rotary kiln application, the system 10 mayrequire or it may be desirable to utilize two or more receivers, such asthe receiver 22, or two or more control units, such as the control unit24. In addition, the system 10 is not restricted to using thermocouples,but may utilize any form of temperature sensing device that can beadapted for use in the furnace or kiln environment for which the system10 is designed.

By way of further example, depending on the configuration of the meltsystem, it may be necessary or otherwise desirable to include in thesystem 10 one or more mass flow controllers or other such heat flowcontrol devices in the recycle system X that are capable of adjustingthe heat flow in the kiln 12. These other heat flow control devices maybe positioned at various locations in the recycle system. Such heat flowcontrol devices may include, for example, a cooling injection port,controllers for various gas supply lines to one or more burners in themelt system, and mechanical in-line dampers for gas flow. It would berecognized by one of ordinary skill in the art that any mechanism thatcan be manipulated to control the heat flow in the kiln 12 maypotentially be incorporated into the system 10. Each of these heat flowcontrol devices can be operatively connected to the control unit 24 suchthat the control unit 24 regulates the heat flow control devices inresponse to the temperature readings transmitted to the control unit 24from the thermocouples 14, 16, 18 and 20. Further, the control unit 24can be programmed to regulate the heat flow control devices in varyingpatterns depending on the profile of the temperature readings across thethermocouples 14, 16, 18 and 20, and the durations of those temperaturereadings at or about any one or more predetermined temperaturesetpoints.

Additional variations or modifications to the configuration of the novelwireless temperature sensing and control system for metal kiln 10 of thepresent invention may occur to those skilled in the art upon reviewingthe subject matter of this invention. Such variations, if within thespirit of this disclosure, are intended to be encompassed within thescope of this invention. The description of the embodiments as set forthherein, and as shown in the drawings, is provided for illustrativepurposes only and, unless otherwise expressly set forth, is not intendedto limit the scope of the claims, which set forth the metes and boundsof our invention.

What is claimed is:
 1. A method for controlling a material processingapparatus comprising a rotary kiln, the kiln having an inlet forsupplying material to the kiln at a feed rate for processing of thematerial in the kiln, an outlet for removal of the material from thekiln after processing, and a process zone positioned between the inletand outlet through which the material moves for processing; theapparatus having a heat source external to the kiln, said heat sourcesupplying heat into the kiln through one of said inlet and said outlet;the process zone having a plurality of temperatures therein positionedat intervals between said inlet and said outlet; the processingapparatus further comprising a plurality of temperature sensors, each ofsaid sensors adapted to measure a temperature at a different locationwithin the process zone positioned at differing distances between saidinlet and said outlet and to generate a signal indicative of thetemperature so measured; the apparatus further comprising one or moreprocess control loops external to the process zone, each of said processcontrol loops indirectly regulating at least in part one or more of theplurality of temperatures within the process zone; the apparatus furthercomprising a programmable microprocessor control unit operativelyassociated with and controlling at least in part each of said processcontrol loops; the method comprising: a. storing a temperature controlprofile in the control unit; b. receiving at the control unit thesignals from the plurality of temperature sensors; c. the control unitdetermining the temperature at each of the locations in the process zoneand creating a process temperature profile of the process zone therefrom; d. the control unit comparing the process temperature profile withthe temperature control profile to create a temperature profilecomparison; and e. the control unit operating one or more of theoperation control loops in response to the temperature profilecomparison in order to adjust the temperature at one or more of thelocations in the process zone in order to substantially match theprocess temperature profile to the temperature control profile.
 2. Themethod of claim 1, wherein the processing apparatus comprises one ormore of the following process control loops operatively associated withthe control unit: i. an overtemp control loop; ii. a material feed ratecontrol loop; iii. a return blower speed control loop; iv. a kilnrotation speed control loop; v. a return gas diverter valve controlloop; vi. a combustion gas control loop; vii; viii. an exhaust dampercontrol loop; xi. an emergency vent control loop; and/or x. an oxygencontrol loop; the method further comprising one or more of said processcontrol loops sensing an operational condition outside of the processzone that influences one or more of said plurality of process zonetemperatures, and each of said one or more process control loopscommunicating a signal indicative of its respective operationalcondition to the control unit; the method further comprising the controlunit receiving and utilizing each said communicated signal to operateone or more of the process control loops in response to one or more ofsaid operational conditions to substantially match the processtemperature profile to the temperature control profile.
 3. The method ofclaim 2, wherein the process zone comprises a plurality of reactionzones, the temperature control profile comprises a plurality oftemperature ranges, and each of said temperature ranges corresponds toone of said reaction zones, each of said plurality of temperaturesensors being positioned in a different one of said reaction zones, thetemperature control profile being segmented into zones corresponding inposition to said reaction zones to create a reaction zone temperatureprofile; the method further comprising the control unit creating acorrelation between the temperatures measured for each said reactionzone and the temperature range from the temperature control profilecorresponding to said reaction zone.
 4. The method of claim 2, whereinthe material feed rate control loop comprises a variable feed ratemechanism operationally controlled by the control unit such thatincreasing the feed rate increases the volume of process material in thekiln to decrease the temperature in the kiln and decreasing the feedrate decreases the volume of process material in the kiln to increasethe temperature in the kiln; the method further comprising the controlunit instructing the feed rate mechanism to increase the feed rate whenthe process temperature profile indicates a temperature in proximity tothe inlet that is greater than the corresponding temperature in theprocess control profile in proximity to the inlet, and instructing thefeed rate mechanism to decrease the feed rate when the processtemperature profile indicates a temperature in proximity to the inletthat is lower than the corresponding temperature in the process controlprofile in proximity to the inlet.
 5. The method of claim 2, wherein thereturn blower speed control loop comprises a recirculation blower and aspeed control mechanism that controls the operating speed of the blower,the blower directing exhaust air from the kiln back into the kiln, thespeed control mechanism being operationally controlled by the controlunit such that increasing the blower speed increases the temperature inthe kiln and reducing the blower speed decreases the temperature in thekiln; the method further comprising the control unit instructing thespeed control mechanism to increase the blower speed when the processtemperature profile indicates a temperature in one or more of thereaction zones that is lower than the corresponding temperature in theprocess control profile, and instructing the speed control mechanism todecrease the blower speed when the process temperature profile indicatesa temperature in one or more of the reaction zones that is greater thanthe corresponding temperature in the process control profile.
 6. Themethod of claim 2, wherein the kiln rotation speed control loopcomprises a variable speed drive that rotates the kiln and a speedcontrol mechanism that controls the operating speed of the drive, thespeed control mechanism being operationally controlled by the controlunit such that increasing the kiln rotation speed increases the rate atwhich process material travels through the kiln and increases thetemperature in the kiln, and that decreasing the kiln rotation speeddecreases the rate at which process material travels through the kilnand reduces the temperature in the kiln; the method further comprisingthe control unit instructing the speed control mechanism to increase thekiln rotation speed when the process temperature profile indicates atemperature in one or more of the reaction zones that is greater thanthe corresponding temperature in the process control profile, andinstructing the speed control mechanism to decrease the kiln rotationspeed when the process temperature profile indicates a temperature inone or more of the reaction zones that is lower than the correspondingtemperature in the process control profile.
 7. The method of claim 2,wherein the apparatus heat source comprises a burner, the return gasdiverter valve control loop comprises an expandable opening thatregulates the volume of gas exiting the kiln that is directed to theburner, the valve being operationally controlled by the control unitsuch that expanding the valve opening increases the volume of return gasdirected to the burner to reduce the temperature of the gases enteringthe kiln, and reducing the valve opening decreases the volume of returngas entering the burner to increase the temperature of the gasesentering the kiln; the method further comprising the control unitinstructing the return gas diverter valve to expand the valve openingwhen the process temperature profile indicates a temperature in one ormore of the reaction zones that is greater than the correspondingtemperature in the process control profile, and instructing the returngas diverter valve to reduce the valve opening when the processtemperature profile indicates a temperature in one or more of thereaction zones that is lower than the corresponding temperature in theprocess control profile.
 8. The method of claim 2, wherein the apparatusheat source comprises a burner, the combustion gas control loopcomprises a mass flow controller that regulates the flow of combustiongas entering the burner, the mass flow controller being operationallycontrolled by the control unit such that increasing the flow ofcombustion gas into the burner increases the temperature in the kiln anddecreasing the flow of combustion gas into the burner decreases thetemperature in the kiln; the method further comprising the control unitinstructing the mass flow controller to increase the flow of combustiongas into the burner when the process temperature profile indicates atemperature in the kiln that is lower than the corresponding temperaturein the process control profile, and instructing the mass flow controllerto decrease the flow of combustion gas into the burner when the processtemperature profile indicates a temperature in the kiln that is greaterthan the corresponding temperature in the process control profile. 9.The method of claim 2, wherein the exhaust damper control loop comprisesan exhaust valve with an expandable opening that regulates the volume ofexhaust gas allowed to exit the apparatus, the valve being operationallycontrolled by the control unit such that expanding the opening increasesthe volume of exhaust gas allowed to exit the apparatus to reduce thegaseous pressure in the kiln and reducing opening decreases the volumeof exhaust gas allowed to exit the apparatus to increase the gaseouspressure in the kiln; the apparatus further comprises an oxygen sensorpositioned to sense the oxygen level of the kiln, the oxygen sensorcommunicating said oxygen level to the control unit; the apparatusfurther comprises a gas pressure sensor positioned to sense the gaseouspressure in proximity to the kiln, the pressure sensor communicatingsaid pressure to the control unit; the control unit being adapted tocorrelate one or more of said oxygen level, said gaseous pressure andthe process temperature profile, to detect a potential flash conditionin the kiln and to determine when said potential flash conditionsubsides; the method further comprising the control unit instructing theexhaust valve to reduce the opening when the control unit detects thepotential flash condition in the kiln, and instructing the exhaust valveto increase the opening when the control unit determines that thepotential flash condition has subsided.
 10. The method of claim 9,wherein the emergency vent control loop comprises a vent valveoperatively associated with the control unit, the vent valve opening toexhaust the gases in the apparatus to atmosphere; the control unitfurther adapted to correlate one or more of said oxygen level, saidgaseous pressure and the process temperature profile, to detect a flashcondition in the kiln and to determine when said flash conditionsubsides; the method further comprising the control unit instructing thevent valve to open when the control unit detects flash condition in thekiln.
 11. The method of claim 2, wherein the oxygen control loopcomprises an oxygen sensor and an oxygen flow controller, the oxygensensor sensing the oxygen level in proximity to the kiln andcommunicating said oxygen level to the control unit, the oxygen flowcontroller operatively communicating with an oxygen source to controlthe flow of oxygen from said source into the kiln, said oxygen flowcontroller being operatively associated with the control unit; the feedrate control loop comprises a variable feed rate mechanism operationallycontrolled by the control unit such that increasing the feed rateincreases the volume of process material and heat in the kiln anddecreasing the feed rate decreases the volume of process material andheat in the kiln, the feed rate control loop communicating the feed rateto the control unit; the apparatus further comprising a material controlchute that communicates to the control unit the rate at which processmaterial is directed into the kiln through the chute; the method furthercomprising providing the control unit with a volatization coefficientfor the process material being placed into the kiln; the control unitcalculating the volume of process material in the kiln; the control unitusing the volalization coefficient, the feed rate and the volume ofprocess material in each reaction zone, at least in part, to determine aprocess temperature for the kiln to outgas volatiles from the processmaterial without a flash over; the control unit determining a targetoxygen level for the kiln to substantially exhaust the volatiles fromthe process material in the kiln without a flash over; the control unitdetermining the oxygen level in the kiln from the oxygen sensor; and thecontrol unit instructing the oxygen flow controller to release oxygeninto the kiln as needed to maintain the target oxygen level.
 12. Amethod for controlling a material processing apparatus comprising arotary kiln, the kiln having an inlet for supplying material to the kilnat a feed rate for processing of the material in the kiln, an outlet forremoval of the material from the kiln after processing, and a processzone positioned between the inlet and outlet through which the materialmoves for processing; the apparatus having a heat source external to thekiln, said heat source supplying heat into the kiln through one of saidinlet and said outlet; the apparatus further comprising a plurality oftemperature sensors positioned at intervals along the length of theprocess zone from the inlet to the outlet, each of said sensorsmeasuring a temperature in one of a plurality of different processregions in the process zone and generating a signal indicative of thetemperature so measured, each of said regions having a processtemperature therein; the apparatus further comprising a plurality ofprocess control loops external to the process zone, each of said processcontrol loops indirectly regulating at least in part one or more of theprocess temperatures in the process zone; the apparatus furthercomprising a programmable microprocessor control unit operativelyassociated with and controlling at least in part each of said one ormore process control loops; the method comprising: a. storing atemperature control profile in the control unit, said temperaturecontrol profile having a plurality of control profile sectors, eachsector corresponding to one of said plurality of process regions in theprocess zone; b. receiving at the control unit the signals from theplurality of temperature sensors; c. the control unit determining fromsaid signals the temperature for each of the plurality of processregions in the process zone; d. the control unit making a comparisonbetween the temperature of each process region and its correspondingcontrol profile sector temperature; e. the control unit identifying fromsaid comparison each process region that is out of temperaturecompliance with its corresponding control profile sector; f. the controlunit identifying two or more of said plurality of process control loopsconfigured to regulate at least in part the temperature of each suchnoncompliant process region, at least one of said two or more processcontrol loops is configured to regulate at least in part the temperatureof a plurality of such noncompliant process regions; and g. the controlunit simultaneously controlling the operation of said two or moreprocess control loops to collectively adjust the temperature of said twoor more noncompliant process regions so as to substantially bring saidnoncompliant process regions into temperature compliance with thetemperature control profile.
 13. The method of claim 12, wherein atleast one of said two or more process control loops is configured toregulate at least in part the temperature of all such noncompliantprocess regions.
 14. The method of claim 12, wherein all of said two ormore process control loops are configured to regulate at least in partthe temperature of a plurality of such noncompliant process regions. 15.The method of claim 12, wherein the temperature control profilecomprises a temperature range for one of said process regions within theprocess zone.
 16. The method of claim 12, wherein the process zonecomprises a delacquering zone.